This study develops a new acoustic negative-refraction metamaterial that utilizes a synthesized double split hollow sphere (DSHS) for its unit cell. Recent relevant research has affirmed the concept that acoustic metamaterials can show unusual behavior that has not been observed in nature previously. However, as some hypothetical metamaterial designs have material properties not found in nature, the realization of practical metamaterials requires practical and complicated models. As a contribution to the development of acoustic metamaterials, the present study proposes a new anisotropic unit structure that encompasses Helmholtz resonators. This structure is referred to as the DSHS, is easy to manufacture, and has the advantage in that it uses the natural medium in its original form. By drawing the equifrequency or isofrequency contours of the designed two-dimensional (2D) anisotropic unit structure using the Floquet–Bloch’s principle, the properties of the present metamaterial can be understood. Numerical simulations are also conducted to identify and present the characteristics of the presented acoustic metamaterial. Through these, a new refraction phenomenon is identified that deviates from Snell’s law, and an acoustic hyperlens is numerically implemented that overcomes the diffraction limit.

中文翻译：

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基于双分割空心球的负向声学Hyperlens

本研究开发了一种新的声学负折射超材料，该材料利用合成的双分裂空心球 (DSHS) 作为其晶胞。最近的相关研究证实了声学超材料可以表现出以前在自然界中未观察到的不寻常行为的概念。然而，由于一些假设的超材料设计具有自然界不存在的材料特性，因此实际超材料的实现需要实用且复杂的模型。作为对声学超材料发展的贡献，本研究提出了一种新的各向异性单元结构，包括亥姆霍兹谐振器。这种结构被称为DSHS，易于制造，并且具有使用原始形式的天然介质的优点。通过使用 Floquet-Bloch 原理绘制设计的二维 (2D) 各向异性单元结构的等频或等频轮廓，可以了解本超材料的特性。还进行了数值模拟以识别和呈现所呈现的声学超材料的特性。通过这些，识别出一种偏离 Snell 定律的新折射现象，并在数值上实现了克服衍射极限的声学 hyperlens。